U.S. patent number 5,350,031 [Application Number 08/079,923] was granted by the patent office on 1994-09-27 for plural generator apparatus for an electric hybrid automobile.
This patent grant is currently assigned to Mitsubishi Denki Kabushiki Kaisha. Invention is credited to Yutaka Kitamura, Takeshi Sugiyama.
United States Patent |
5,350,031 |
Sugiyama , et al. |
September 27, 1994 |
Plural generator apparatus for an electric hybrid automobile
Abstract
A power generation apparatus for an electric hybrid automobile.
Two a.c. generators 21, 22 which have different rotation speeds at
the initiation of power generation and which provide high
efficiency at or near the different rotation speeds are driven by
an internal combustion engine 1 via a belt 23. An a.c. power is
supplied to a rectifier 4, and the power is used as a power source
for an induction motor 7 and a battery 5.
Inventors: |
Sugiyama; Takeshi (Himeji,
JP), Kitamura; Yutaka (Himeji, JP) |
Assignee: |
Mitsubishi Denki Kabushiki
Kaisha (Tokyo, JP)
|
Family
ID: |
16489209 |
Appl.
No.: |
08/079,923 |
Filed: |
June 23, 1993 |
Foreign Application Priority Data
Current U.S.
Class: |
180/65.245;
903/903; 903/907 |
Current CPC
Class: |
B60K
6/46 (20130101); B60W 10/08 (20130101); B60L
50/10 (20190201); B60K 6/28 (20130101); H02J
7/1415 (20130101); B60K 6/48 (20130101); B60L
50/61 (20190201); Y02T 10/72 (20130101); Y02T
10/70 (20130101); Y02T 10/7072 (20130101); Y10S
903/907 (20130101); Y10S 903/903 (20130101); B60L
2220/12 (20130101); Y02T 10/62 (20130101); B60K
2006/4833 (20130101) |
Current International
Class: |
B60L
11/12 (20060101); B60L 11/02 (20060101); B60K
6/00 (20060101); B60K 6/04 (20060101); H02J
7/14 (20060101); B60K 001/02 () |
Field of
Search: |
;180/65.1
;322/44,45,25 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0394481 |
|
Oct 1990 |
|
EP |
|
429504 |
|
Apr 1992 |
|
JP |
|
295252 |
|
Aug 1928 |
|
GB |
|
1288587 |
|
Sep 1972 |
|
GB |
|
1312699 |
|
Apr 1973 |
|
GB |
|
Primary Examiner: Camby; Richard
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak and
Seas
Claims
We claim:
1. A power generation apparatus for an electric hybrid automobile,
said power generation apparatus comprising:
a) a plurality of a.c. generators commonly driven in parallel by an
internal combustion engine (1) through a rotation transmitting
means (23),
b) a rectifier (4) for rectifying a.c. output voltages of the a.c.
generators,
c) a battery (5) charged with an output from the rectifier,
d) a control device (6) supplied with a d.c. voltage from the
rectifier of the battery, for converting the d.c. voltage into a
variable frequency a.c. voltage by means of a stationary inverter,
and
e) an induction motor (7) supplied with a.c. power by the control
device for driving an automobile,
f) one of the a.c. generators having a relatively low rotation
speed at the initiation of power generation, and another one of the
a.c. generators having a relatively high rotation speed at the
initiation of power generation.
2. The power generation apparatus according to claim 1, wherein two
a.c. generators are used, and a control voltage applied to the a.c.
generator having a relatively low rotation speed at the initiation
of power generation is lower than a control voltage applied to the
a.c. generator having a relatively high rotation speed at the
initiation of power generation.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a power generation apparatus for
an electric hybrid automobile having a.c. generators which are
driven by an internal combustion engine and serve as a power source
for an induction motor for cruising.
FIG. 3 is a diagram showing a conventional power generation and
moving mechanism of an electric hybrid automobile provided with a
power generation apparatus. In FIG. 3, reference numeral 1
designates an internal combustion engine, numeral 2 designates an
a.c. generator driven by the internal combustion engine 2 through a
belt-connection means 3 at a rotation speed of three times as fast
as a rotation speed of the engine, numeral 4 designates a rectifier
for rectifying an a.c. voltage of the a.c. generator 2 into a d.c.
voltage, numeral 5 designates a battery as an auxiliary d.c. power
source, which is charged with an output voltage of the rectifier 4,
and numeral 6 designates a control device which controls an
exciting current in the a.c. generator by means of a voltage
regulator by detecting an output voltage of the rectifier 4 to
thereby effect voltage regulation, and converts a d.c. voltage from
the rectifier 4 into an a.c. voltage by means of a stationary type
inverter. The control device 6 also changes the frequency of the
a.c. voltage. Numeral 7 designates an induction motor which
receives the a.c. voltage under the control of the control device
6. The rotation speed of the induction motor is controlled by the
change of the frequency of the a.c. voltage by the control device
6. Numeral 8 designates a differential gear to which the rotational
force of the induction motor 7 is transmitted. The differential
gear 8 rotates the wheels 10 through an axle 9.
The internal combustion engine has an operating zone at or near
3,000 rpm as a rated engine speed which provides the most effective
fuel consumption efficiency. In that operating zone, the operation
for a substantially constant rotation speed is conducted. The
internal combustion engine 1 has another operating zone at or near
4,000 rpm which is used when the maximum speed or the maximum
acceleration is necessary for the automobile, and another operating
zone in a range of 1,000 to 1,500 rpm when the automobile is
operated with the battery 5 fully charged, or when the automobile
is stopped for a long time. Accordingly, for the a.c. generator 2
used for a conventional automobile, there is a requirement that the
output current characteristics corresponding to the engine rotation
speed should satisfy values at three points I.sub.1, I.sub.2 and
I.sub.3 of an output current from of the rectifier which are
indicated by X marks in FIG. 4. In order to satisfy the
above-mentioned output current characteristics, the size of the
a.c. generator 2 is necessarily large. The output voltage of the
rectifier 4 is, for instance, 280 V and the voltage of the battery
5 is, for instance, 240 V.
The conventional power generation apparatus for an electric hybrid
automobile has the following disadvantages. Since the single a.c.
generator 2 to be driven has to bear the supply of power so as to
cover a rotation speed range from a rotation speed the idling of
the combustion engine 1 to a rotation speed which corresponds to
the maximum power of the automobile, the size of the generator 2 is
necessarily large, and the efficiency of the operation of the
engine is low at the rated engine speed at which a high efficiency
is necessary (usually, the operation of the engine at the rated
engine speed is most frequently used). Further, there is difficulty
in mounting and arranging the large-sized generator 2 on the
internal combustion engine 1. Further, since the size of the
generator 2 is large, a fairly large-sized belt connection means 3
which connects the a.c. generator 2 to the internal combustion
engine 1 is required.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a power
generation apparatus for an electric hybrid automobile which
provides a power generation characteristics suited for the
characteristics required for the internal combustion engine of the
electric hybrid automobile, has a small size, and allows highly
efficient operations.
It is another object of the present invention to provide a power
generation apparatus for an electric hybrid automobile which
facilitates mounting on an internal combustion engine and reduces
the size of a driving force transmitting means for generators.
In accordance with the present invention, there is provided a power
generation apparatus for an electric hybrid automobile
comprising:
an a.c. generator driven by an internal combustion engine through a
rotation transmitting means,
a rectifier for rectifying an a.c. voltage of the a.c.
generator,
a battery charged with an output from the rectifier,
a control device which is supplied with a d.c. voltage from the
rectifier or the battery, and converts the d.c. voltage into an
a.c. voltage with a change of frequency by means of a stationary
type inverter, and
an induction motor which is supplied with an a.c. power by the
control device to drive an automobile,
the power generation apparatus being characterized in that a
plurality of a.c. generators are provided, and they have different
rotation speeds at the initiation of generation of power.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of an electric hybrid automobile provided with
a power generation apparatus according to a first embodiment of the
present invention;
FIG. 2A is a characteristic curve of the power generation apparatus
shown in FIG. 1 wherein the output current characteristic vs. the
engine rotation speed of the power generation apparatus is shown as
an output current of a rectifier;
FIG. 2B is a diagram showing the efficiency of each of a.c.
generators, in FIG. 1, vs. the engine rotation speed;
FIG. 3 is a diagram showing a conventional electric hybrid
automobile provided with a power generation apparatus and auxiliary
means;
FIG. 4 is a characteristic curve of the conventional a.c. generator
in FIG. 3 wherein the output current characteristic vs. the engine
rotation speed is shown as an output current of a rectifier;
and
FIG. 5 is a diagram showing another embodiment of the electric
hybrid automobile according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described
with reference to FIGS. 1 and 2.
FIG. 1 is a diagram showing an electric hybrid automobile provided
with a power generation apparatus and auxiliary means according to
the first embodiment of the present invention. In FIG. 1, reference
numerals 1 and 4 through 10 designate the same elements as in FIG.
3.
Numeral 21 designates a first a.c. generator which has a low
rotation speed at the initiation of power generation and which
shows high efficiency in a low rotation speed region. The first
a.c. generator has a small capacity and a small size in comparison
with the conventional generator described with reference to FIG.
3.
Numeral 22 designates a second a.c. generator which has a high
rotation speed at initiation of generation of power and which shows
high efficiency in a high rotation speed region. The second a.c.
generator also has a small capacity and a small size in comparison
with the conventional generator.
The first and second a.c. generators 21, 22 are connected to the
internal combustion engine 1 by means of a common rotation
transmitting means 23 such as a belt connection means so that power
generated in both generators is supplied to the rectifier 4. The
size of the rotation transmitting means 23 can be reduced since it
transmits a rotating force of the internal combustion engine 1 to
the small-sized a.c. generators 21, 22. The rotation speed of the
generators 21, 22 is increased to, for instance, three times by
means of the rotation transmitting means 23.
FIG. 2A shows the output current characteristics of the a.c.
generators 21, 22 vs. the engine rotation speed in terms of the
output current of the rectifier, wherein a broken line indicates
the characteristic curve A obtained by the first a.c. generator 21
and a one-dotted chain line indicates the characteristic curve B
obtained by the second a.c. generator 22. A solid line shows the
total or combined output current of the first and second a.c.
generators 21, 22. The solid line passes near the three points
I.sub.1, I.sub.2 and I.sub.3 and covers satisfactorily these three
points. Accordingly, the first and second a.c. generators do not
excessively generate power, they can be of a small capacity.
With the a.c. generators 21, 22, the output voltage of the
rectifier 4 is, for instance, 280 V. The first a.c. generator 21
having the characteristic A initiates the generation of power at a
rotation speed of 1,500 rpm or lower (such as 1,200 rpm). The
second a.c. generator 22 having the characteristic B initiates the
generation of power at a rotation speed of 3,000 rpm or lower (such
as 2,700 rpm).
FIG. 2B shows characteristic curves showing the efficiency of each
of the a.c. generators 21, 22 vs. engine rotation speeds wherein
the characteristic A indicates the efficiency of the a.c. generator
21 and the characteristic B indicates the efficiency of the a.c.
generator 22.
Generally, a non-load voltage per phase is expressed by E=K.PHI.Zf
wherein K is a constant, .PHI. is the number of magnetic fluxes per
pole, Z is the number of series winding conductors per phase, f is
frequency (f=(P/2).times.(N/60), P is the number of poles and N is
rotation speed.
In the characteristic A of the first a.c. generator having a low
rotation speed at the initiation of power generation, f is small
while Z is large. On the other hand, in the characteristic B having
a high rotation speed at the initiation of power generation, f is
large while Z is small. When the value of Z is large, the
resistance of the stator coil is large whereby copper loss is large
and the efficiency is reduced. Further, armature reaction due to a
magnetic field which is produced by the passing of an armature
current is large, and the output is reduced to thereby reduce the
efficiency. Accordingly, in the first a.c. generator 21 having a
large value of Z and a low rotation speed at the initiation of
power generation, the efficiency is reduced in a high rotation
speed region whereby it shows the characteristic curve A in FIG.
2B. On the other hand, in the second a.c. generator 22 having a
small value of Z and a high rotation speed at the initiation of
power generation, the efficiency is high in a high rotation speed
region whereby it shows the characteristic curve B in FIG. 2B. In
the conventional power generation apparatus, the rotation speed at
the initiation of generation of power is the same as the
characteristic curve A in FIG. 2B and the efficiency is the same as
the characteristic curve A.
In a second embodiment of the present invention, the control
voltage for the first a.c. generator 21 having the characteristic
curve A is determined to be lower than the control voltage for the
second a.c. generator 22 having the characteristic curve B. By
determining these control voltages, the second a.c. generator 22
which is more efficient than the first a.c. generator 21 dominantly
shares a load in operation at the rated engine speed (such as 3,000
rpm) whereby a further high efficient operation is obtainable.
In the above-mentioned embodiments, two a.c. generators 21, 22
having different rotation speeds at the initiation of power
generation are used. However, three or more a.c. generators may
also be used.
FIG. 5 is a diagram showing still another embodiment of the present
invention wherein a third a.c. generator 24 is used in addition to
the first and second generators 21, 22. The same reference numerals
as in FIG. 1 designate the same elements.
Further, in the above-mentioned embodiments, the belt connection
means is used as the rotation transmitting means 13 for the
generators. However, another rotation transmitting means such as a
chain connection means or a gear connection means may be used.
As mentioned above, in accordance with the present invention, a
plurality of a.c. generators having different rotation speeds at
the initiation of power generation, and providing high efficiency
at or near the rotation speeds are connected for supplying power to
an internal combustion engine by means of a rotation transmitting
means. Accordingly, power generation characteristics suited for the
operation characteristic required for the internal combustion
engine for an electric hybrid automobile can be obtained; the size
of each of the a.c. generators be reduced; flexibility in arranging
the a.c. generators be increased; and the size of the rotation
transmitting means can be reduced. The power generation apparatus
can be driven with the own characteristics of the a.c. generators,
and efficiency can be increased because highly efficient operation
is obtainable with a large output by the generator providing a high
efficiency at or near the rated engine speed. A further highly
efficient operation is obtainable by determining a control voltage
for the generator having a low rotation speed at the initiation of
power generation to be lower than the generator having high
rotation speed at the initiation of power generation.
* * * * *